Second, KL12 relax the H00 assumption of strictly AMC winds by assuming that the Rossby number (\(\) ) is uniform throughout each Hadley cell but not necessarily unity. Its formal definition follows below, but for now \(\)  is exactly unity for AMC winds and vanishes for vanishing zonal winds, and KL12 derive an analytical expression for the meridional profile of zonal wind under uniform \({0<\le 1}\) .
In simulations [1]} and reanalysis data [2]}, \(\)  is regularly below unity and typically smaller in the equinoctial and summer cells than in the cross-equatorial winter cell [3]}, [4]}. By diagnosing a bulk value of \(\)  for each cell and meteorological season in addition to \(\) , KL12 provide closed expressions for the northern and southern hemisphere descending edge latitudes in all four seasons.In addition to KL12, other authors have considered a uniform \(\)  in the tropical upper troposphere. [5]} find that a uniform \({=0.5}\)  approximation (their Fig. 7 and Eq. 28) adequately captures the vorticity distribution in the descending branch of the winter Hadley cell in their simplified, dry GCM. And [6]} discuss the absolute vorticity distribution corresponding to uniform \(\) .
